Revert "hal: add support to separate headset and headphones mixer backend"

This reverts commit 6c5e87cca33a93a59a5ed890a6fff6bb3a51e659.
Test: manual usb phone test
Bug: 114178494

Change-Id: I07c72aad45e7fc9f08876a71db58948721aa9519
1 file changed
tree: 547529416ecbc3c2a89ba3197d28f090fb46f1af
  1. hal/
  2. legacy/
  3. post_proc/
  4. visualizer/
  5. voice_processing/
  6. Android.mk